1. Field of the Invention
The present invention relates to rights expression systems for controlling use of digital works and other items. In particular, the present invention is directed to rights expression systems that facilitate creation and/or modification of rights expressions in a rights expression language based on one or more schemas.
2. Description of Related Art
Digital distribution of content by content owners over the Internet is a way to reach out to a potentially large market of Internet users. However, such digital distribution comes with a risk of illegal, or otherwise unauthorized, distribution of the content. Rights Management helps reduce this risk thereby enabling content owners to protect and profit from their digital content. A Rights Management System is utilized to specify the usage rights for content, or other things and to enforce the usage rights. The term “content” is used broadly herein and includes digital works such as music, audio files, text files, books, reports, video, multimedia, pictures, executable code, or any combination thereof.
Various implementations of Rights Management Systems and rights associated with digital content are known as disclosed by U.S. Pat. No. 5,629,980, U.S. Pat. No. 5,634,012, U.S. Pat. No. 5,638,443, and U.S. Pat. No. 5,715,403. Hence, the details of Rights Management Systems are not discussed specifically herein. As evident from these references, a Rights Management system can take many forms, and can employ varying levels of complexity depending on the security required, the nature of the thing being managed, the complexity of associated rights and conditions, volume and other factors. For example, Rights Management systems have been used to enable the secure distribution of digital media content over the Internet. Examples of such systems and associated paradigms are Pay-per-view, Subscription, and Superdistribution, as well as others. A Pay-per-view paradigm may require the user to pay a fee each time content is viewed. A Subscription paradigm may allow subscribers who pay monthly to download a number of songs per month. A Superdistribution paradigm may encourage the free and widespread distribution of digital content, such as audio or video clips, that can only be opened a limited number of times.
A Rights Management system not only protects content, but it also enables content owners to manage the sale and use of their content by means of licenses. Licenses include rights expressions to articulate usage rights and to associate usage rights to a content. Licenses may be specified for different stages during the life cycle of digital content. For example, when digital content is released to a distributor, licenses may be specified by content owners to limit distribution of the digital content to a particular region or a period of time, or to restrict how content may be repackaged. Of course, licenses themselves must be protected as well since they are a controlling facet determinative of how content is used. Typically, licenses are digitally signed by the issuers so that their integrity and authenticity may be verified before being interpreted. Before being signed, a license is known as an unsigned license.
Licenses may also stipulate terms and conditions applied to the rights offered by content owners. For example, a license to support a Subscription paradigm may require that the user pay $10.00 monthly to download up to 10 songs per month. A license to support a Pay-per-View paradigm may require the user to pay $5.00 to play a movie. A more dynamic license may specify approval from an online approval service before usage to the digital content is granted. Licenses must accommodate the flexible business rules that help generate sales for content and ensure that content owners are compensated rightfully for the use of their content.
A rights expression is a syntactically and semantically correct language construct, based on a defined grammar that conveys rights information. Licenses written in a Rights Expression Language (hereinafter “REL”) can support multiple rights granting paradigms, ranging from simple to more complex, since the REL provides the syntactically and semantically correct construct and grammar for describing rights information. Rights information may include rights and conditions concerning the content. An example of a REL is XrML™ which allows a clearly defined way to structure, describe, and interchange rights data. Rights expressions written in XrML may be understood by different systems, enabling interoperability between these systems. Of course, XrML is merely one example of a REL and other RELs may also be used.
XML schema is an ongoing effort by the W3C to describe the structure of conforming XML documents, including provisions for defining data types. An XML schema may describe the structure and terms provided by a REL. For example, an instance of an XML schema, called “Core”, may define a rights expression called “grant” to include four different types, namely, “principal”, “right”, “asset”, and “condition”. This expression stipulates that the indicated principal is granted the stated right over associated content under the given conditions.
The schema may also be extended to include new terms that are appropriate to a specific industry or rights granting paradigms. It is the extensibility of XML schema that empowers the REL to be adapted to any current, or new rights granting paradigms, and any industries. For example, a music company may seek to adopt the grammar specified by the XML schema using its own vocabulary. The music company creates an extension of this schema, called “S1”, defining a new principal called “subscriber”, a new right called “play”, a new asset called “music content X0”, and a new condition called “online”. The music company may then create expressions such as “any subscriber can play music content X0 online”.
A second music company who allows downloads may define yet another extension, called “S2”, to include a right called “download” for building expressions such as “any subscriber can download music content X0”, assuming the grammar defines the condition to be optional. Note that S1 extends the original schema Core, enabling it to use any definitions provided by Core. Also, since S2 extends S1, S2 may use definitions provided by both S1 and Core. The above exemplary Core schema is described using XML Schema syntax in FIG. 13. As can be appreciated, the Core schema basically defines a grant that includes four different types: principal, right, resource and condition in the present example.